The deposition of zinc-bearing layers onto substrate surfaces finds widespread application in many areas of engineering. Zinc-bearing layers are particularly distinguished by their high corrosion resistance. Due to the appearance of the zinc coatings obtained, zinc layers or zinc-bearing layers are used less in the area of decorative coatings, but rather in the area of functional coatings. So, for example, it is common to coat small parts such as, for example, screws, nuts, and base washers, and pre-assembled structural elements such as angle iron or connecting plates and the like in large numbers. To do this, multiple small parts are dipped into appropriate deposition baths in so-called drum baskets and a deposition current is applied between the deposition basket and an anode.
Often another metal is deposited underneath the zinc, which may affect the properties obtained for the zinc-bearing layer deposited. In particular, the appearance, the corrosion resistance, and the mechanical properties of the layers deposited are influenced by appropriate alloy coatings. So, for example, zinc-manganese alloys for deposition are known from DE 103 06 823 A1. The galvanic deposition of zinc-nickel alloys is described in De 101 46 559.
Iron, cobalt, and nickel as alloy metals are known from DE 195 38 419 A1 for deposition together underneath zinc.
One problem with the galvanic deposition of zinc-bearing layers onto substrate surfaces from an acidic zinc-bearing electrolyte is that it takes place using zinc anodes which are depleted to form coatings on the anode surface, which these passivate and affect the production cycle detrimentally. The effectiveness of the galvanic deposition can also be reduced by these coatings.